include/linux/timer.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_TIMER_H
   3 #define _LINUX_TIMER_H
   4
   5 #include <linux/list.h>
   6 #include <linux/ktime.h>
   7 #include <linux/stddef.h>
   8 #include <linux/debugobjects.h>
   9 #include <linux/stringify.h>
  10
  11 struct timer_list {
  12         /*
  13          * All fields that change during normal runtime grouped to the
  14          * same cacheline
  15          */
  16         struct hlist_node       entry;
  17         unsigned long           expires;
  18         void                    (*function)(struct timer_list *);
  19         u32                     flags;
  20
  21 #ifdef CONFIG_LOCKDEP
  22         struct lockdep_map      lockdep_map;
  23 #endif
  24 };
  25
  26 #ifdef CONFIG_LOCKDEP
  27 /*
  28  * NB: because we have to copy the lockdep_map, setting the lockdep_map key
  29  * (second argument) here is required, otherwise it could be initialised to
  30  * the copy of the lockdep_map later! We use the pointer to and the string
  31  * "<file>:<line>" as the key resp. the name of the lockdep_map.
  32  */
  33 #define __TIMER_LOCKDEP_MAP_INITIALIZER(_kn)                            \
  34         .lockdep_map = STATIC_LOCKDEP_MAP_INIT(_kn, &_kn),
  35 #else
  36 #define __TIMER_LOCKDEP_MAP_INITIALIZER(_kn)
  37 #endif
  38
  39 /*
  40  * A deferrable timer will work normally when the system is busy, but
  41  * will not cause a CPU to come out of idle just to service it; instead,
  42  * the timer will be serviced when the CPU eventually wakes up with a
  43  * subsequent non-deferrable timer.
  44  *
  45  * An irqsafe timer is executed with IRQ disabled and it's safe to wait for
  46  * the completion of the running instance from IRQ handlers, for example,
  47  * by calling del_timer_sync().
  48  *
  49  * Note: The irq disabled callback execution is a special case for
  50  * workqueue locking issues. It's not meant for executing random crap
  51  * with interrupts disabled. Abuse is monitored!
  52  */
  53 #define TIMER_CPUMASK           0x0003FFFF
  54 #define TIMER_MIGRATING         0x00040000
  55 #define TIMER_BASEMASK          (TIMER_CPUMASK | TIMER_MIGRATING)
  56 #define TIMER_DEFERRABLE        0x00080000
  57 #define TIMER_PINNED            0x00100000
  58 #define TIMER_IRQSAFE           0x00200000
  59 #define TIMER_ARRAYSHIFT        22
  60 #define TIMER_ARRAYMASK         0xFFC00000
  61
  62 #define TIMER_TRACE_FLAGMASK    (TIMER_MIGRATING | TIMER_DEFERRABLE | TIMER_PINNED | TIMER_IRQSAFE)
  63
  64 #define __TIMER_INITIALIZER(_function, _flags) {                \
  65                 .entry = { .next = TIMER_ENTRY_STATIC },        \
  66                 .function = (_function),                        \
  67                 .flags = (_flags),                              \
  68                 __TIMER_LOCKDEP_MAP_INITIALIZER(                \
  69                         __FILE__ ":" __stringify(__LINE__))     \
  70         }
  71
  72 #define DEFINE_TIMER(_name, _function)                          \
  73         struct timer_list _name =                               \
  74                 __TIMER_INITIALIZER(_function, 0)
  75
  76 /*
  77  * LOCKDEP and DEBUG timer interfaces.
  78  */
  79 void init_timer_key(struct timer_list *timer,
  80                     void (*func)(struct timer_list *), unsigned int flags,
  81                     const char *name, struct lock_class_key *key);
  82
  83 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
  84 extern void init_timer_on_stack_key(struct timer_list *timer,
  85                                     void (*func)(struct timer_list *),
  86                                     unsigned int flags, const char *name,
  87                                     struct lock_class_key *key);
  88 #else
  89 static inline void init_timer_on_stack_key(struct timer_list *timer,
  90                                            void (*func)(struct timer_list *),
  91                                            unsigned int flags,
  92                                            const char *name,
  93                                            struct lock_class_key *key)
  94 {
  95         init_timer_key(timer, func, flags, name, key);
  96 }
  97 #endif
  98
  99 #ifdef CONFIG_LOCKDEP
 100 #define __init_timer(_timer, _fn, _flags)                               \
 101         do {                                                            \
 102                 static struct lock_class_key __key;                     \
 103                 init_timer_key((_timer), (_fn), (_flags), #_timer, &__key);\
 104         } while (0)
 105
 106 #define __init_timer_on_stack(_timer, _fn, _flags)                      \
 107         do {                                                            \
 108                 static struct lock_class_key __key;                     \
 109                 init_timer_on_stack_key((_timer), (_fn), (_flags),      \
 110                                         #_timer, &__key);                \
 111         } while (0)
 112 #else
 113 #define __init_timer(_timer, _fn, _flags)                               \
 114         init_timer_key((_timer), (_fn), (_flags), NULL, NULL)
 115 #define __init_timer_on_stack(_timer, _fn, _flags)                      \
 116         init_timer_on_stack_key((_timer), (_fn), (_flags), NULL, NULL)
 117 #endif
 118
 119 /**
 120  * timer_setup - prepare a timer for first use
 121  * @timer: the timer in question
 122  * @callback: the function to call when timer expires
 123  * @flags: any TIMER_* flags
 124  *
 125  * Regular timer initialization should use either DEFINE_TIMER() above,
 126  * or timer_setup(). For timers on the stack, timer_setup_on_stack() must
 127  * be used and must be balanced with a call to destroy_timer_on_stack().
 128  */
 129 #define timer_setup(timer, callback, flags)                     \
 130         __init_timer((timer), (callback), (flags))
 131
 132 #define timer_setup_on_stack(timer, callback, flags)            \
 133         __init_timer_on_stack((timer), (callback), (flags))
 134
 135 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
 136 extern void destroy_timer_on_stack(struct timer_list *timer);
 137 #else
 138 static inline void destroy_timer_on_stack(struct timer_list *timer) { }
 139 #endif
 140
 141 #define from_timer(var, callback_timer, timer_fieldname) \
 142         container_of(callback_timer, typeof(*var), timer_fieldname)
 143
 144 /**
 145  * timer_pending - is a timer pending?
 146  * @timer: the timer in question
 147  *
 148  * timer_pending will tell whether a given timer is currently pending,
 149  * or not. Callers must ensure serialization wrt. other operations done
 150  * to this timer, eg. interrupt contexts, or other CPUs on SMP.
 151  *
 152  * return value: 1 if the timer is pending, 0 if not.
 153  */
 154 static inline int timer_pending(const struct timer_list * timer)
 155 {
 156         return timer->entry.pprev != NULL;
 157 }
 158
 159 extern void add_timer_on(struct timer_list *timer, int cpu);
 160 extern int del_timer(struct timer_list * timer);
 161 extern int mod_timer(struct timer_list *timer, unsigned long expires);
 162 extern int mod_timer_pending(struct timer_list *timer, unsigned long expires);
 163 extern int timer_reduce(struct timer_list *timer, unsigned long expires);
 164
 165 /*
 166  * The jiffies value which is added to now, when there is no timer
 167  * in the timer wheel:
 168  */
 169 #define NEXT_TIMER_MAX_DELTA    ((1UL << 30) - 1)
 170
 171 extern void add_timer(struct timer_list *timer);
 172
 173 extern int try_to_del_timer_sync(struct timer_list *timer);
 174
 175 #ifdef CONFIG_SMP
 176   extern int del_timer_sync(struct timer_list *timer);
 177 #else
 178 # define del_timer_sync(t)              del_timer(t)
 179 #endif
 180
 181 #define del_singleshot_timer_sync(t) del_timer_sync(t)
 182
 183 extern void init_timers(void);
 184 extern void run_local_timers(void);
 185 struct hrtimer;
 186 extern enum hrtimer_restart it_real_fn(struct hrtimer *);
 187
 188 #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
 189 struct ctl_table;
 190
 191 extern unsigned int sysctl_timer_migration;
 192 int timer_migration_handler(struct ctl_table *table, int write,
 193                             void __user *buffer, size_t *lenp,
 194                             loff_t *ppos);
 195 #endif
 196
 197 unsigned long __round_jiffies(unsigned long j, int cpu);
 198 unsigned long __round_jiffies_relative(unsigned long j, int cpu);
 199 unsigned long round_jiffies(unsigned long j);
 200 unsigned long round_jiffies_relative(unsigned long j);
 201
 202 unsigned long __round_jiffies_up(unsigned long j, int cpu);
 203 unsigned long __round_jiffies_up_relative(unsigned long j, int cpu);
 204 unsigned long round_jiffies_up(unsigned long j);
 205 unsigned long round_jiffies_up_relative(unsigned long j);
 206
 207 #ifdef CONFIG_HOTPLUG_CPU
 208 int timers_prepare_cpu(unsigned int cpu);
 209 int timers_dead_cpu(unsigned int cpu);
 210 #else
 211 #define timers_prepare_cpu      NULL
 212 #define timers_dead_cpu         NULL
 213 #endif
 214
 215 #endif